Flexible hose of plastics material has been used for many years to facilitate the operation of swimming pool cleaners. Where these cleaners are of the kind which operate automatically through the pool filtration system it has been found that the characteristics of the hose have an important influence on the operation of the pool cleaner.
The hose presently available is made to a corrugated longitudinal cross-section to provide radial stiffness to the hose with flexibility both along and transverse to the axis of the hose.
To date the hose used with swimming pool cleaners has been made from extruded plastics material and this inherently requires that the hose be made with two parts which are adhered together in the manufacturing process. This has the disadvantage that the manufacture makes it impossible to have a constant wall thickness for the hose. This can result in either an undesirable stiffness against flexing of the hose or alternatively a tendency for the hose to collapse under the internal reduced pressure experienced during use. The corrugations follow a helical path and this also has an adverse effect on the desired flextural characteristics.
The manufacturing technique enables the hose to be made in a continuous length but this necessitates cutting of the hose into appropriate lengths. However a further disadvantage is that male or female couplings components must be separately manufactured and fitted or moulded to the ends of the tube lengths.
Several different recipes of plastics material are used and these have been found to enable proper use of the swimming pool cleaner to be obtained. Not all hoses are suited to all cleaners but the appropriate recipe is readily ascertainable by persons skilled in the art.
The hoses are made to a compromise to give reliable use over a reasonable period of time and at reasonable cost.